1. Field of the Invention
This invention relates to load carrying packs that are strapped to the back of a person. Further the invention relates to a structure for the load carrying pack that is intended to protect the posture of the spinal column from deformity.
2. State of the Prior Art
There are numerous designs for packs or sacks that are strapped to the body of a person for purposes of carrying personal items while leaving the arms free of the items carried. There are so called back packs, fanny packs, and other types of sack like packs that are strapped to the body for purposes of carrying items for the person wearing the pack.
In the past and prior to the advent of the present invention the load bearing packs are essentially designed to distribute the load being carried so as to accentuate the normal curvature of the spinal column. This leads to spinal column deformity either of a temporary nature or permanent deformity of the spinal column.
The spinal column consists of twenty four vertebra which are constructed of bone. Between each bony vertebra is a so called cartilaginous disk called the spinal disk. These spinal disks are subject to compression forces and to torsional forces during the day and usually compensate for these forces. The spinal column has three major curves called the cervical curve, the thoracic curve, and the lumbar curve. There are six cervical vertebra comprising the cervical curve of the spine. The thoracic curve is comprised of twelve thoracic vertebra and the lumbar curve is comprised of six lumbar vertebra. The normal cervical curve and the normal lumbar curve of the spine are concave inwards. The normal thoracic curve is convex inwards.
While the spinal column can withstand considerable compression pressure or force it is vulnerable to torsional forces or forces that are horizontal to the spinal column. Accentuation of the normal curvature of the spinal column can result in deformity. For example the condition known as kyphosis is an exaggeration of the normal thoracic curvature of the spine. It can be caused by poor posture or excessive force on the thoracic spine. Lordosis is another abnormal spinal column condition which is an exaggeration of the lumbar curvature of the spine. It can be caused by increased by increased weight in the region of the abdomen or by forces of a horizontal nature on the spinal column.
All spinal column deformities are exaggerations of the normal curvature of the spine or are lateral bending of the spinal column. This leads the conclusion that forces antagonistic to the normal curvature of the spinal column result in compensation by the intervertebral disks and do not cause spinal column deformity. On the other hand it is reasonable to conclude that forces on the spinal column that accentuate the normal curvature of the spine can lead to temporary or even permanent deformity of the spine.
Young persons attending school must of necessity carry relatively large loads of books and other school materials. For example a young person attending school weighing 75 pounds could be forced to carry 25 pounds of books and other school materials. Additionally the young student may be required to ascend and descend stairs throughout the day causing additional forces and pressures on the skeleton of the young person. In young persons who are growing in size the skeletal system of the body of such a person is in a stage of development and is vulnerable to forces and pressures on the spinal column and other bones of the body.
In the past there have been numerous so called packs for carrying items for the personal and leaving the arms and hands free but these designs tend to accentuate and thereby distort the normal curvature of the spinal column.
Thatcher in U.S. Pat. No. 5,114,059 discloses a frameless back pack that is claimed to be universally adjustable. This back pack is designed to concentrate the load in the back pack to the hips and lumbar spinal column of the user. Since the load would be concentrated at least in part over the lumbar spinal column this invention would promote deformity of the spinal column.
For example Gleason in U.S. Pat. No. 5,487,498 discloses a so called fanny pack or back pack which is worn over the back of a person and designed to concentrate the weight of the pack at the region of the lumbar curvature of the spine. Clearly this concentration of weight is likely to result in accentuation of the normal lumbar curvature of the spine and the abnormal condition known as lordosis.
Another lumbar pack is disclosed in U.S. Pat. No. 5,529,230 by Smith. Again this lumbar pack would exert a force that accentuates the normal lumbar curvature of the spine leading to either temporary or permanent deformity of the spinal column.
The desirability of concentration of the forces of a carrying pack on the thoracic region of the spine is recognized by Theodore in U.S. Pat. No. 5,950,896. This patent discloses a front pack structure with a lumbar strap that tends to exert pressure on the thoracic area of the spine and thereby promote good posture. This invention, however, teaches away from the back pack of the present invention.
There has been a long felt need for a carrying pack that promotes good posture especially in young school children. Accordingly it is one objective of the present invention to disclose a back pack that exerts its carrying load at the thoracic spine of the person. This force is exerted against the normal thoracic spinal curvature which tends to promote good posture by not accentuating spinal curvature. It is the accentuated spinal curvature that results in deformity of the spine.
Another object of the present invention is to disclose a transparent carrying structure that permits visual inspection of the contents of the pack. This is desirable in schools due to the possibility of the student carrying harmful or dangerous things in the pack.
The objectives of the present invention are accomplished by using straps on the back pack that distribute the forces of the load carried in the pack to the thoracic area of the spinal column.